There are those who argue that voting for a third party is not a wasted vote. Vote for a third party because you actually believe in one of those candidates. Vote for a third party candidate as a protest of your dissatisfaction with the choice of major party nominees. Vote for a third party candidate as a message of dissent to the major parties that they must do better and nominate superior candidates. Vote for a third party candidate as a moral choice. Vote for a third party candidate because you cannot bring it upon yourself to vote for Hillary Clinton or Donald Trump but still wish to punish them electorally. Voting for a third party candidate, or an independent candidate, is your right to exercise if you so choose. American voters are free to do with their vote as they wish, and in an election in which the major party candidates are widely unpopular voters are looking for an alternative. And as the vast majority of the American electorate did not nominate Hillary Clinton or Donald Trump, dissatisfaction with the nominees is understandable.
There are approximately 324 million people in the United States. Of these 324 million, approximately 219 million are eligible to vote. Out of these 219 million who could have voted in the primaries, about 28 million voted in the Democratic primaries/caucuses while about 28.5 million voted in Republican primaries. This means only 25.8 percent of all eligible voters voted in the primaries. In the Democratic primaries/caucuses Hillary Clinton won approximately 16 million votes while in the Republican primaries Donald Trump won approximately 13.5 million votes. Out of all eligible voters Hillary Clinton gained about 7 percent and Donald Trump about 6 percent. Therefore, only 13 percent of the American electorate chose Hillary Clinton and Donald Trump has their nominees.
In the 2012 presidential election there were approximately 129 million votes cast in total. Of these 129 million votes about 127 million were cast for one of the two major party candidates, Barack Obama (~66 million) and Mitt Romney (~61 million). Assuming the same level of turnout in 2016, the same number of combined major party nominee votes, and the same distribution of those votes, that would mean only 30 percent of all eligible American voters elected Hillary Clinton or Donald Trump.
Therefore, by simple math a vote for a non-major party candidate is not a wasted vote. However, this ignores the fact that the United States uses plurality-rule elections with single-member districts. This means representatives are elected by who receives the most votes and there can be only one winner, and this heavily favors a two-party system. Voting for a non-major party candidate is not necessarily a wasted vote, but you won’t be electing the president. A third-party candidate has never been elected president. But a third-party candidate is not the only option.
Any number of Democrats wish Bernie Sanders was the nominee. Many Republicans may rather have Ted Cruz, Marco Rubio or John Kasich as their nominee. These were the main primary opponents of Clinton and Trump and would have had the best chance of winning outside of Clinton and Trump. If all of these candidates were able to remain in the race until Election Day, how would they fare?
Hillary Clinton won the Democratic popular vote in the primaries/caucuses over Bernie Sanders by 3.8 million votes. Clinton won 29 primaries/caucuses versus 19 for Bernie Sanders. Using popular primary votes as a proxy for general election votes and translating state wins in Electoral College votes, this would mean Hillary Clinton gained 387 votes compared to 116 votes for Bernie Sanders.
Donald Trump won the Republican popular vote in the primaries over Ted Cruz by 5.7 million votes, John Kasich by 9.2 million votes, and Marco Rubio by 10 million votes. Trump won 36 states versus 9 states for Ted Cruz, 1 for John Kasich, and 2 states for Marco Rubio. Using the same primary to general election proxy, Donald Trump gained 408 Electoral College votes compared to 84 votes for Ted Cruz, 18 votes for John Kasich, and 13 votes for Marco Rubio.
Given these numbers for the candidates it is difficult to imagine anyone besides Hillary Clinton or Donald Trump being able to win the general election on November 8th. While these numbers would most likely change over the course of the election cycle as more information was revealed about the candidates and as they competed against candidates from the opposing party, the numbers would most likely not shift significantly enough to alter the electoral numbers. Trump supporters have rarely wavered in their candidate preference, no matter what others say. While Cruz or Kasich or Rubio may have been able to gain more support from the Republican base, it may not have made much of a difference. The Republican base is under increasing pressure to accommodate Trump supporters, not the other way around. And while Bernie Sanders still maintains a level of support, especially among younger voters, his general support among Democrats lags far behind.
In reality, the primary contests weren’t close. Hillary Clinton and Donald Trump won because they were the preferred candidates of their respective parties. By a wide margin. No other Democrats stood much of a chance against Hillary Clinton and no other Republicans stood a chance against Donald Trump. And these potential candidates most likely would have more support in the general election than any non-major party candidate because it is important to consider that any discussion of voting for a third-party candidate and it not being a wasted vote must take into account the electoral system of the United States. A system which institutionally discourages non-major party candidates.
Hillary Clinton and Donald Trump are the nominees because they are the two most popular individuals in the race and have been for months. You can vote for a candidate other than Clinton or Trump, but that candidate will not win. That candidate will not gain a significant number of votes. It will not make the major parties reconsider their nominations. It is a wasted vote.